So i have a 2 year old Compaq laptop whose battery is almost dead. It gives me a backup of 20 minutes to the max. Its a 6 Cell Battery.

Now my questions:

1. From where in NCR should i buy a new battery with warrenty ?
2. Are there different types of batteries for the same laptop ?
3. How much would a 6 Cell Battery cost ?
4. Can i fix a 9 Cell battery instead of a 6 Cell to get better backup ?
5. If yes then what are the so called side effects of doing the same ?

TIA

Switch